Current tentage is generally made without thermal insulation protection. A need exists for an insulation liner for air conditioned and heated tents to be utilized as mobile field hospitals. It was initially determined that this insulation liner should provide a 6.0 R value (.degree.F.-hr-ft.sup.2 /BTU) of insulation based upon the thermal loads expected and the cooling capacity of the air conditioner to be utilized. In addition to the insulation properties, a thermal insulation liner should be of minimal weight and thickness, with low moisture absorption. The initial approach tried in developing a thermal insulation liner was to employ a system including synthetic microfiber battings. Microfibers with diameters less than 10 micrometers reduce radiation heat flow to a greater extent than regular fibrous batting materials comprised of fibers having a diameter of about 25 micrometers. A liner consisting of cover fabrics together with insulative layers of synthetic microfiber battings more than met the desired insulation requirements, but the synthetic microfibers are high in cost and the liner employing it had a greater weight per unit area than desired.
Further research led to the novel thermal insulation liner of the instant invention which is 40% lighter in weight than the above-described microfiber batting liner. The liner of this invention provides optimum insulative properties through the use of radiant heat reflective plies together with low density flame retardant polyester batting. Additionally, this liner provides good flame resistance through use of fiberglass cover fabrics and the flame retardant batting.